<!DOCTYPE html>
<!-- Passes if there is a blue rounded-corner rect below the gray one -->
<div style="width: 200px; height: 200px; isolation: isolate; will-change: transform; background: lightgray">
  <div id=border-radius style="border-radius: 10px; overflow: hidden; position: relative; top: 300px; width: 100px; height: 100px;">
    <div id=child style="width: 100px; height: 100px; background: lightblue; will-change: transform"></div>
  </div>
</div>
